Newton's Second Law of Motion


A girl pulls her little brother on a sled across a frozen lake, and friction is so small you can ignore it. The sled with the boy has a weight of 400 Newtons, and the girl pulls with a force of 100 N at an angle of thirty degrees above the horizontal.

Q1: Draw this situation. Include the weight of the sled, the normal force and the force on the sled due to the girl's pull.

Q2: Calculate the normal force of the ice on the sled. Notice it is not equal to the weight of the sled and the boy. Explain this in your own words.

Q3: Calculate the net force on the sled in the horizontal direction. Calculate the corresponding initial acceleration of the sled.

Q4: If the girl can maintain this acceleration for 1.5 seconds, how fast will the sled be moving then?



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